Epoxy Ding Repair Kit

Here is a dumb problem. The kit is the basic repair kit at most shops but for epoxy. Nearly 48 hours later it is still soft(unsandable) in some spots. Repair was done two days ago at noon outdoors so it was not cold. Properly mixed at 2/1 ratio. What is the best way to solve this? I have one experience with epoxy resin before this but did not have this problem. Thanks